The CM-9521 rotator and 9537 controller do not share wire/coax with the signal from the antenna. I can't think of a failure in any part of the rotator system that would cause interruption of the signal from the antenna so long as the antenna is pointing in the right direction. This sounds like movement of the antenna caused something to come loose or break.
http://www.channelmaster.com/v/vspfi...july10_web.pdf
"Syncing" the controller and rotator can cause a nearly full rotation of the antenna. If there was existing wear or stress of the coax, a "Sync" operation could cause final failure of the coax, leaving the rotator operational but the signal from the antenna disconnected.